Harry w



H. W. HARDINGE.

GRINDING MILL AND GRINDING MEDIUM'THEREFOR.

APPLICATION FILED .IULY 8,1920. I

1,388,463. Patented Aug. 23-, 1921* Fig. 2

IIIIIIHIIIIIIIII IIIIIIIIIIIIIIIIIIHHIIIIIIIIIIIIIIIIIIII I INVENTOR i/Lr A TORNEYS UNITED SI -E 1 'AI T OFFICE- HARRY w. ARDINGE, or NEW YORK, N'. Y., Ass'rGNoR To I-IARDINGE COMPANY, or

: NEW XORK, 'N. Y., A CORPORATION OF DELAWARE.

" enmiNe-MILLnNn GRINDING MEDIUM rnnnnron.

To allwhom z'tmay concern: 1 7

Beit known that I, HARRY W. .H RDINGE, a citizen of the United States of America, residing at 'NewfYork, in the county and State ofNew York, have invented certain new and useful Improvementsin Grinding- Mills and Grinding Media Therefor, of

. objects to provide grinding mediaparticularly adapted to disintegrate the-material acted upon by an abrasive or tearing apart,

. which the following is a full, clear, and exact description.

This invention relates to the art of grinding mills and has for one of its principal action.

Grinding mills embodying a rotatable barrel or drumcontaininga multiplicity of loose grinding members or media are now well known in the art. The barrel or drum assumes various forms such as a cylinder, cone or other suitable shape. The loose *grinding mediaassume the form of balls,

pebbles, rods, etc. The grinding mediaroll and tumble about freely in the rotation of the drum and disintegrate thematerial fed to the mill primarily by animp'act action.

I have found that disintegration by impactaction or pounding is often injurious and ruinous to certain;ma.terial, particularly fibrous material such as jute, wood'- pulp, etc. Moreover, the time and power required to reduce such'material as well as copper, brass, aluminum, etc. (which resist the hammer action of pounding and rolling bodies) to' a given degree of fineness are comparatively high'in magnitude. The above mentioned materials are more effectively and efficiently reduced to fines or powder by an abrasive tearing rather than by the crushing impact which is most effective in breakingup quartz and similar materials.

Inordento secure the desired abrasive 7 action I have devised comparatively flat grinding members which possess little or no tendency to roll when rotated in the mill of which they form a part, but rather slide and abrade or tear the material lying between each grinding member and its neighbors.- Other objects and advantages will appear in view of'the following disclosure of some of the various specific forms which the invention may assume. 7 a

Referring to the drawingsfwhich illustrate what I now consider preferred forms of my invention.

v Specification of Letters Patent. Patented Aug. 23, 1921.

Application filed July 3, 1920. Serial No. 394,636.,

Figure 1 is an elevation of one of the numerous forms of mills in which my grindlng media may be employed.

Figs. 2 and 3 are respectively a plan view and a side elevation of one form of grinding member. i

Fig. 4 is a view similar to Fig. 2 but illustrating a modified form of grinding member.

1 Fig. 5 is a section onthe line 5-5 of Figs. 6' and 7 are elevations of two further modifications which may havethe apperance, in plan,illustrated in Figs. 2 and 4; respectively;

- Fig. 8 is a diagrammatic view employed in explaining the operation of the invention.

It will be understood that the grinding media forming a part of the present invention may be employed in various types of mills such as cylindrical, conical, etc., and

the inventionincludes such use. In order to avoid surplusage in illustration and description and because the conical mill is at present preferred by me I have illustrated only a form of the last mentioned type of mill; Calling attention toFig. 1 it will be seen that'the mill there illustrated comprises ahollow drum 1 having a conical outlet portion 2 and mounted for rotation in bearings 3, 3 by means of a gear wheel 1 and suitable impelling means (not shown). Material to be ground or disintegrated may be introduced through the inlet trunnion 5, and after having been reduced to the desired fineness in the clrum,the resulting fines are discharged through the outlet trunnion 6. The drum 1 has loosely mounted therein a'multiplicity of-fiat (as compared to balls) grinding members 7 which may assume various forms as will hereinafter appear.

One form of grinding member is illus trated in Figs. 2 and 3 and is in the form of a fiat discus shaped element of metal or other suitable material. It will be apparent that-when a multiplicity of such members are contained or placed in a conical or other drum 1 they tend to assume the relative position illustrated in full lines in Figs. 1 and 8. The reason for this is that this is the position of stable equilibrium of the members 7. As the drum 1 rotates the upper members 7 slide or slip' down over the adjacent members,rinstead' of rolling down, and thereby tear or separate by abrasion the material in the interstices between the said members.

Fig. 8. In order for any member 7 to roll it must assume the position shown in dotted lines in the last mentioned figure. Due to the fact that this is an exceedingly unstable position the chance that any member 7 will assume this dotted line position or that it' will maintain such position for an appreciable length of time is so remote as to be practicably negligible.

In order to enhance the abrading or tearingaction the surfaces of the members 7 may be roughened or rendered grid-like as indicated in F ig. 2 (the surfaces being shown smooth in Fig. 3 for the sake of clearness in illustration). Instead of, or in addition to roughening the surfaces of the memhere 7, each of said members may be provided with openings 8 extending into or through the members. These openings, when provided, accomplish a very important re sult especially when grinding wet pulp or similar material. Thematerial flows into and fills the said openings and joins the material lying on each side of the members 7 by what may be termed a plurality of keys similar to the keys which hold plaster or cement to lathing. During the operation of the mill and the consequent sliding of each member 7 across its neighboring members the fibrous pulp or other material is effectively torn apart.

While the form of grinding member specfically described above is at present preferred by me it will be obvious that it may be modified without departing from the scope of the broadest claims hereinafter stated. For example instead of employing circular discus-like members, flat discus'like members having polygonal edges may be employed, asindicated in Figs. 4 and 5. Or fiat cylinders or flat prisms or ovals may be employed as indicated in Figs. 6 and 7 respectively.

If a conical mill, and such a mill is illustrated in Fig. 1, is employed it will be borne in mind that there is an inherent classification-by size on the interior of the drum 1 particular will be all of the same size, an important' effect may be achieved by providing members of varying sizes. It will be apparent that the abrasive action between a member 7 and its lower neighbors is to a large extent dependent on the weight and therefore size of the member. When the material "is coarsest, '5. 6., at or adjacent the base of the cone 2, it is desirable to exert the maximum abrasive action and it is desirable progressively to diminish this abrasive action as the material decreases in size, in other words in the direction ofapproach to the outlet 6. If, as above stated, the members 7 employed in a mill such as the one illustrated are of varying sizes they will be automatically classified according to size in the same manner that the material is. g The result is that the abrasive action will be a maximum at or adjacent the base of the cone 2 and will gradually diminish in the direction of the outlet opening.

In accordance with the provisions of the patent statutes, I have herein described the principle of operation of my inventiomtogether with the apparatus which Inow consider to represent the best embodiments thereof, but I desire to have it understood that the apparatus disclosed is only illustrative and that the invention can be carried out by other means. Also, while it, is designed to use the various features and elements in the combination and relation described, some 7 of these may be altered and others omitted without interfering with the more general results outlined, and the invention extends to such use.

What I claim is: V

1; A grinding mill comprising inr'eombination, a rotatable drum containing a multiplicity of discus-shaped elements relatively slidable with respect to each other and free to assume a position in which their geometrical axes are at a substantial angle to the axis of rotation of said drum, each of said elements comprising two cone portions; secured base to base, the altitude of each cone portion being small as compared to the diameter of its base. 7

2. A grinding mill comprising in combination, a rotatable drum containing a multiplicity of discus-shaped elements relatively slidable with respect to each other and free to assume a position in which their geometrical axes are at a substantial angle to the axis of rotation of said drum, each of said elements comprising two cone portions secured base to base, the altitude of each cone portion being small as compared to the diameter of its base, and each of said elements having a plurality of openings extending therethrough from one face to the other.

In testimony whereof I hereto ailix my signature.

. HARRY W. HARDINGE. 

